AresMUSH
A New Breed of MUSH Server

Arg Parsers

  • [code]
  • [plugins]
  • [commands]

An important part of command handling is parsing arguments. Arguments coming out of the Command class are raw strings. Ares provides a variety of argument parsing utilities to handle command args that are intended to be interpreted as numbers, lists, or even complex sequences like “name=subject/message”.

Arg Converters

Arg converters alter the format of the argument string - changing it to a number, a list, a titlecased string, etc. They are part of the Command Handler class, so they can be used by any command handler.

  • trim_arg - Strips leading and trailing spaces from an arg.
  • titlecase_arg - Capitalizes words (like a title). Also strips spaces like trim_arg.
  • upcase_arg - Makes every letter uppercase. Also strips spaces like trim_arg.
  • upcase_arg - Makes every letter lowercase. Also strips spaces like trim_arg.
  • integer_arg - Interprets the arg as a number. Returns 0 if you give it a non-numeric string.
  • list_arg - Splits an argument into an array. Splits on spaces by default, but you can pass any delimeter.
  • trimmed_list_arg - Splits an argument into an array and strips spaces on each entry like trim_arg. Splits on spaces by default, but you can pass any delimeter.
  • titlecase_list_arg - Splits an argument into an array and strips spaces and formats each entry like a title. Splits on spaces by default, but you can pass any delimeter.
def parse_args
  self.value = downcase_arg(cmd.args)
end

Arg Parsers

The ArgParser class helps to split up commands that are in more complex formats, like “mail players=subject/message”. It is used in conjunction with the cmd.parse_args method. For example:

def parse_args
  args = cmd.parse_args(ArgParser.arg1_equals_arg2)
  self.property = downcase_arg(args.arg1)
  self.value = titlecase_arg(args.arg2)
end

The first line cracks apart the arguments and stores them in ‘args’. Then we can access the pieces with things like args.arg1 and args.arg1.

There are a variety of common parsers available, described in more detail below.

Under the hood, a parsers like ArgParser.arg1_equals_arg2 is just a fancy regular expression that matches the pieces of the commands and assigns names to them (arg1 and arg2 in this case). cmd.parse_args is a method that uses one of those fancy regexes and stores the results in an easily-accessed hash (args).

arg1_equals_arg2

This is probably the most commonly-used parser, intended for commands where you’ve got a target and a value.

describe object=description
channel/alias channel=alias

arg1_equals_optional_arg2

Similar to arg1_equals_arg2, this version allows the second arg to be optional. It is commonly used on commands that can work on yourself or on an optional target.

group/set myfaction or group/set player=faction
channel/join channel  or  channel/join channel=alias

arg1_slash_arg2

Less common than its ‘equals’ counterpart, this version is usually used when there’s a target and a more detailed identifier.

bbs/read board/number
look object/detail

arg1_slash_optional_arg2

Similar to arg1_slash_arg2, this version allows the more detailed identifier to be optional.

mail/review char vs mail/review char/#
combat/join combat_number or  combat/join combat_number/combatant_type

arg1_equals_arg2_slash_arg3

This parser appears when there’s a target followed by multiple pieces of information. It is commonly used in admin commands where the syntax is “command player=thing/value”.

demographic char=hair/haircolor
mail to list=subject/message

arg1_equals_arg2_slash_optional_arg3

This version is similar to arg1_equals_arg2_slash_arg3 but allows the second piece of information to be optional.

mail/fwd mail_number=char or mail/fwd mail_number=char/comment
combat/join npc=combat_number or combat/join npc=combat_number/combatant_type

arg1_slash_arg2_equals_arg3

This very uncommon parser is used to act on items that have multiple identifiers.

bbs/deletereply board/post_num/reply_num